Cell Shuttling in Multifunctional Microsized Needles

Microsized platforms are crucial for injectable cell delivery systems acting as cell carriers to improve the delivery and retention efficacy at the injury site. The design of these cell‐supporting platforms is critical in these applications with key features such as size, geometry, or surface chemistry playing a major role in the modulation of cell functions such as adhesion and proliferation. Bottom‐up wet chemistry routes involve a much more subtle design, while offering in return easier processability and scalability, which are critical in the context of cell delivery platforms. In this study, we present the bottom‐up synthesis and spontaneous formation of innovative micrometer‐sized needles from polyoxometalate hybrids to be used as cell carriers. The quasi 1D geometry of the microneedles provides a high surface‐to‐volume ratio, ≈twofold of a spherical carrier of equivalent volume, enhancing cell adhesion. Their unique needle‐like shape facilitates retention at the delivery site. The microneedles demonstrate a cytocompatibility of around 95%, promoting spontaneous cell adhesion even in the presence of adherent substrates. Additionally, magnetic functionalization of the microneedle surfaces enables controlled mobility, orientation, 3D tracking, and fixation in bioengineered tissues.